We have identified a gene encoding a PfArf 1 protein which contains a conserved amino-terminal glycine for the myristoylation site and consensus sequences for GTP-binding motif. PfArfl transcript was detected predominantly in the asexual erythrocytic stage of merozoites, while the transcript of a P falciparum Rab homologous gene was detected only in the sexual stages. The E. coli expressed PfArf 1 exhibits both PLD and ADP- ribosylation activity. In addition, we have determined the genomic structure of Pfhsp60 gene which contains a single intron disrupting the open reading frame. In contrast to the pronounced induction of Pfhsp60 transcripts during heat shock, the level of Pfhsp60 remains relatively constant at raised temperatures. This result suggested that the existence of additional post-transcription control for Pfhsp60 expression. EM study using specific antibody raised against recombinant pfhsp60 confirmed that the protein is predominantly localized in mitochondria as suggested by the mitochondria targeting sequence previously identified on the amino terminus of this protein.